ckfeister
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1. Find the quadratic equation whose roots are (α + 1) and (β + 1), where α and β are the roots of the equation 2x2 - 11x + 1 = 0.

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Answer is
2x2 - 15x + 14 = 0 ... how?
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ckfeister
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Mr M
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(Original post by ckfeister)
1. Find the quadratic equation whose roots are (α + 1) and (β + 1), where α and β are the roots of the equation 2x2 - 11x + 1 = 0.

Answer is
2x2 - 15x + 14 = 0 ... how?
Rotate the picture please.

You need to find the sum of the new roots (\alpha + 1) + (\beta + 1) = \alpha + \beta + 2 and the product of the new roots (\alpha + 1) (\beta + 1) = \alpha \beta + \alpha + \beta + 1. You should hopefully then know what to do.
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ckfeister
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(Original post by Mr M)
Rotate the picture please.

You need to find the sum of the new roots (\alpha + 1) + (\beta + 1) = \alpha + \beta + 2 and the product of the new roots (\alpha + 1) (\beta + 1) = \alpha \beta + \alpha + \beta + 1. You should hopefully then know what to do.
I don't get why its rotated like that and tried re-sending and it goes upside down... how do I rotate on TSR as phone is being useless
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Mr M
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(Original post by ckfeister)
I don't get why its rotated like that and tried re-sending and it goes upside down... how do I rotate on TSR as phone is being useless
It doesn't matter. I've stood on my head now.
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HapaxOromenon3
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(Original post by ckfeister)
1. Find the quadratic equation whose roots are (α + 1) and (β + 1), where α and β are the roots of the equation 2x2 - 11x + 1 = 0.

Name:  Capture.PNG.jpg
Views: 131
Size:  302.8 KB

Answer is
2x2 - 15x + 14 = 0 ... how?
If the new roots are a+1 and b+1, then their sum is a+b+2, which is 11/2+2 = 15/2.
Similarly their product is (a+1)(b+1) = ab+a+b+1 = 1/2+11/2+1=7.
Hence the new equation is x^2 - (15/2)x + 7 = 0, and doubling gives 2x^2 - 15x + 14 = 0, as required.
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Mr M
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(Original post by HapaxOromenon3)
...
Please read the Guide To Posting at the top of the Maths Forum. Providing full solutions is against the rules. You should just give hints to move people forward in their learning.
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ckfeister
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The answer is
x2 + 8x + 216 = 0, I get x2 - 8x + 216 = 0, anyone get why I got (+8x) instead of (-8x) ?
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RDKGames
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(Original post by ckfeister)

The answer is
x2 + 8x + 216 = 0, I get x2 - 8x + 216 = 0, anyone get why I got (+8x) instead of (-8x) ?
The sign changes for the sum when you construct the new quadratic.

Remember, the new quadratic is Ax^2+Bx+C=0 so the sum of roots is \alpha^3 +\beta^3=-\frac{B}{A} \Rightarrow \frac{B}{A}=-(\alpha^3 +\beta^3)
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HapaxOromenon3
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(Original post by Mr M)
Please read the Guide To Posting at the top of the Maths Forum. Providing full solutions is against the rules. You should just give hints to move people forward in their learning.
You should know by now that whenever I get banned for this or other infractions, I simply create a new account and start again. Thus you really need to try harder...
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Mr M
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(Original post by HapaxOromenon3)
You should know by now that whenever I get banned for this or other infractions, I simply create a new account and start again. Thus you really need to try harder...
This is the first time I have encountered you but I am disappointed by your reaction. No-one is threatening to ban you or sanction you in any way. I was just asking you nicely to do the right thing.
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Naruke
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(Original post by hapaxoromenon3)
you should know by now that whenever i get banned for this or other infractions, i simply create a new account and start again. Thus you really need to try harder...
loooooooooool.
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